Evidence from numerous fields such as geology, genetics and archeology shows clearly that the flood of the Genesis part of the bible cannot have happened as described there.
That account may have cultural or moral value as a story, but it clearly has none as history.
There are individuals who, in the face of the above, continue to insist that the Noah's flood story actually occurred. What is one to make of this? Has their religiosity actually impaired their ability to reason? Is their stance really political and not based on actual beliefs? What gives?
Historically it's possibly about the swelling of the black sea or any other flood event that became mythical in nature. I also know that the impact of indoctrination is extremely powerful, and even within the most angsty fundamentalist may be a trapped genius.